1. Field of the Invention
The present invention relates to a chain guide including a guide shoe that slidingly guides a running chain and a guide main body that supports the guide shoe in a chain running direction, this chain guide having a reinforcing rib extending in a height direction of the guide main body.
2. Description of the Related Art
A chain guide provided with a guide shoe that slidingly guides a running chain is commonly used for stabilizing the chain that runs between sprockets and maintaining the correct chain tension. A chain guide is known that is provided with a guide main body supporting the guide shoe along the chain running direction and has a reinforcing rib extending in the height direction of the guide main body (see Japanese Patent Application Publication No. 2001-153199).
For example, FIG. 5 shows a well-known timing system of an engine in which a transmission chain CH such as an endless suspended roller chain is caused to run between sprockets S1, S2 provided at a crankshaft and a camshaft, respectively, inside an engine room E. The timing chain CH is endless suspended between the drive sprocket S1 mounted on the crankshaft inside the engine room E and a pair of driven sprockets S2 mounted on the camshaft, and the timing chain CH is guided by a swinging chain guide (swinging guide) 500 and a chain guide (fixed guide) 600.
In such a well-known timing system, the fixed guide 600 is fixed inside the engine room E by two mounting shafts Q, and the swinging guide 500 is mounted inside the engine room E such as to be capable of swinging in the suspension plane of the timing chain CH about the swinging shaft P as a center.
A chain tensioner T maintains the appropriate tension of the timing chain CH and inhibits vibrations by applying pressure to the swinging guide 500.
As shown in FIGS. 6 and 7, the well-known chain guide (swinging guide) 500 used in such a timing system includes a guide shoe 510 and a guide main body 520. The guide main body 520 has a swinging boss portion 523 that is swingably supported through a support wall portion 521 extending to the side opposite that of a sliding guide surface 511 which is a chain running surface, and a pushing portion 524 which is pushed by a tensioner T to the chain side.
Reinforcing ribs 522 extending in the height direction of the guide main body 520 are provided with appropriate spacing, shape, and orientation and increase the rigidity of the guide main body 520.
Lips 512 protruding to the chain side for preventing the chain from slipping off in the width direction are provided at both sides of the sliding guide surface 511 which is the chain running surface of the guide shoe 510.
The chain guide (fixed guide) 600 has a similar structure, except that two fixed boss portions for fixing to two mounting shafts Q are provided instead of the swinging boss portion 523 and the pushing portion 524 of the above-described chain guide (swinging guide) 500.
Further, the chain guide (swinging guide) 500 or the chain guide (fixed guide) 600 in which the guide shoe 510 and the guide main body 520 are integrally formed by injection molding is also well known.